Catheters are flexible medical instruments for use in the introduction and withdrawal of fluids to and from body cavities, ducts and vessels. Catheters are used for many different applications within the human body including the administration of liquid therapeutic agents and the removal of bodily fluids for testing, monitoring, or disposal. Catheters have a particular application in hemodialysis procedures, in which blood is withdrawn from a blood vessel, directed to a hemodialysis unit for dialysis or purification, and subsequently returned to the blood vessel.
Typically, dialysis catheters define at least two lumens including a venous lumen and an arterial lumen. The arterial lumen withdraws blood from the patient and delivers the blood to a dialyzer. The venous lumen receives purified blood from the dialyzer and returns the blood to the patient. The venous and arterial lumens may include distal openings adjacent to the tip of the catheter. In addition, the venous and arterial lumens may also include side openings proximal to the tip of the catheter which provide redundant flow paths to and from the arterial and venous lumens.
One problem associated with known dialysis catheters is the susceptibility of known catheters to the formation of thrombus within the openings of the catheter. Thrombus is a clot which consists of fibrin, platelets, red blood cells and white blood cells that form in the lumen of the catheter. The formation of thrombus adjacent to the side openings of the catheter may result in occlusion of the side openings of the catheter and obstruct, partially or completely, blood flow to or from the catheter. The likelihood of thrombus formation is increased by disruptive blood flow which results in elevated shear stress on the blood.
It would be desirable to provide a catheter having side openings which are configured to improve the flow dynamics of the blood flow into the hemodialysis catheter to minimize the formation of thrombus.